Many species of insects encase their ova in protective sheaths which are impregnable to most toxicants. The gestation period of the egg is often relatively long in comparison to the life cycle of the adult forms. Thus, an agent effective only against adults must persist for the lifetime of the developing ovum, or must be re-applied as successive hatchings occur.
Highly effective insect ovicides having low toxicity to mammals are quite rare.
It has now been found that certain N-acyl sarcosines, i.e., N-acyl-N-methyl glycines, exhibit effective ovicidal activity, often with a useful degree of insecticidal activity. These glycines are well known as surface active agents and have been incorporated in many pharmaceutical and cosmetic preparations as such. For example, tetradecylamine lauroyl sarcosinate has been used in an anti-dandruff preparation and cocoyl sarcosine constitutes greater than 10% of Head and Shoulders shampoo. Cocoyl sarcosine has been used in hair tint shampoos at a pH of 5.5. Dvorokovitz (U.S. Pat. No. 2,890,960) teaches the use of antienzymes including lauryl sarcosinic acid to retard ovideposition in fruit flies.
It is the object of this invention to provide new safe and effective toxicants for insects and their ova. The low mammalian toxicity of the subject compositions and methods renders them especially suitable for the treatment of ectoparasitic diseases, such as lice and scabies, in man and animals. In these applications, the ovicidal properties are particularly noteworthy, both for speed of impact and for potency. This and other objects of the invention will become apparent to those skilled in the art from the following detailed description.